The present invention relates to a fuel supply device for an internal combustion engine incorporating a plurality of cylinders, in particular, a multi-cylinder internal combustion engine in which fuel is fed under control of a fuel injection valve provided to each of cylinders, and also relates to a control apparatus which carries out the control.
Conventionally, there has been known, as a fuel supply system in a fuel supply device in a multi-cylinder internal combustion engine, the so-called sequential fuel injection control system in which fuel is supplied while fuel injection valves incorporated respectively to cylinders are sequentially controlled in synchronization with rotation. In this sequential fuel injection control as is discussed on, for example, page 1004 in "Automobile Technology" Vol, 39, No. 9, 1985, control of beginning of blowing, that is, the initiation of injection is controlled, and control of completion of blowing, that is, the completion of fuel injection is controlled, are carried out. In this control system, the fuel injection volume and the fuel injection timing are determined in view of an engine load which is in turn determined in accordance with an intake-air volume, an engine rotational speed and the like in any one of these controls, and the above-mentioned fuel injection timing is normally carried out during exhaust stroke of each of cylinders, except upon transient caused by an abrupt variation in load.
Namely, in the above-mentioned conventional method, as indicated by a timing chart shown in FIG. 12 of the accompanying drawings, fuel injection for each of the cylinders in the internal combustion engine is carried out such that an injection volume of fuel to be fed into each of the cylinders of the engine is at first obtained through correction on the basis of Qa/N, that is a quotient between an intake air volume Qa and a rotational speed N of the engine, that is, an engine load, with the use of various coefficient factors, and the above-mentioned injection timing as indicated by hatched lines in the timing chart, is carried out during exhaust stroke of each of the cylinder in consideration with a fuel injection period determined corresponding to the above-mentioned fuel injection volume.
However, in the above-mentioned conventional technology, since there has not yet been built up a reasonable system in such a case that a plurality of main factors such as a droplet size of a fuel injection device having air-assist, an operating condition, an optimum fuel injection timing caused by a degree of air-assist and the like are combined with one another, there have caused problems such that THC components in exhaust gas cannot be reduced, and that the fuel efficiency and the drivability cannot be enhanced.